System adapted for diagnosis of large numbers of automotive road vehicles



March 8, 1966 Filed Dec. 6

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6 Sheets-Sheet 6 2J8 LOW VIBRATION PASS METER DETECTOR FILTER l Haul-United States Patent Office 3,238,771 Patented Mar. 8, 1966 SYSTEMADAPATED FGR DIAGNOSIS OF LARGE NUMBERS F AUTOMOTIVE ROAD VEHICLESGeorge B. Myrtetus, Collingswood, Charles H. Pancoast, Pitman, andCharles R. Small, Woodbury Heights, N.J., and Fernando A. Pellicciotti,Inglewood, Calif., assignors to Socony Mobil Oil Company, Inc., acorporation of New York Filed Dec. 6, 1962, Ser. No. 242,847 5 Claims.(Cl. 73-117) This invention relates to automotive vehicle servicing, andmore particularly to systems for thoroughly testing and checkingautomotive vehicles in order to diagnose any conditions needingcorrection.

There have been developed many sophisticated techniques and devices fortesting and checking automotive vehicles for various defects,malfunctionings and other conditions which require correction. Thesetechniques and devices are very specialized and are designed to diagnoseonly very specific conditions. Since there are a large number ofconditions which might require correction, it would be a long drawn-outprocess to thoroughly test an automotive vehicle in order to provide adiagnosis which would diagnose any condition in an automotive vehicleneeding correction, particularly if such condition were not evident tothe operator or owner of the vehicle. As a result, it is noteconomically practical for a vehicle owner to pay to have this kind ofdiagnosis performed or for a garage to perform it. The usual procedureis to wait until trouble becomes disturbing and then perform tests todetermine the cause of the particular trouble and correct it. Thisprocedure often results in increased expense because the condition wasnot corrected soon enough. Moreover, since the vehicle owners are notwilling to pay the cost of thorough testing and checking, it is noteconomically practical for a garage to keep on hand the expensiveequipment required to perform the more sophisticated testing techniques.As a result, many modern testing techniques which would more accuratelydiagnose conditions requiring correction in a vehicle are not availableto the vehicle owner.

The present invention is used in a system for completely testing andchecking many automotive vehicles in a short period of time with justtwo diagnosticians. The testing and checking provides a diagnosis ofalmost any condition requiring correction in the vehicle, even thoughthe condition is not otherwise evident. Because the entire testing andchecking procedure is performed in a short period of time with a minimumof personnel, it can be carried out for a nominal cost and for the firsttime it is economically practical to thoroughly test and checkautomotive vehicles so that conditions can be corrected before theybecome expensive, thus saving the vehicle owner substantial repaircosts. Moreover, the system in which the present invention is used makesit practical to have in one facility equipment for performing the mostmodern and sophisticated tests and checks on vehicles. As a result, moreaccurate diagnosis is made available to the vehicle owner.

In order for the system to be economically practical, the entire testingprocess must be carried out in just a few minutes. Thus time is of theessence and any feature which will save even a few seconds is importantto the system, as it is only by using these time saving features thatthe system becomes economically practical. The present inventionprovides arrangements and combinations of testing equipment which reducethe time to perform the necessary tests on each vehicle and also permitsome of the equipment to perform several functions, thus reducing theamount of equipment required to perform a complete testing operation.The system in which the present invention is used comprises adrive-through diagnostic bay in which the test equipment is located. Inaccordance with the present invention, a dynamometer has its rollerspositioned in the floor of the diagnostic bay to receive the right andleft wheels of an automotive vehicle so that an automotive vehicle canbe driven to the position in which its wheels are on the rollers. Astripchart recorder is provided which receives a signal from thedynamometer indicating the speed at which the dynamometer rollers arerotating and thus the speed at which the wheels of the vehicle are beingdriven. The stripchart recorder also receives a signal from an enginetachometer, which is connected to the ignition system of the vehiclewhen its rear wheels are engaged by the rollers of the dynamometer. Thistachometer applies a signal to the strip-chart recorder representing theengine speed of the vehicle. The strip-chart recorder, upon beingactuated, will graphically record the two applied signals on the samechart. Thus when a vehicle has its rear wheels positioned on the rollersof the dynamometer, a diagnostician can accelerate the vehicle throughall its gears and record the engine speed and the wheel speed duringthis process. Then by observing the resulting graph, the operation ofthe transmission system of the vehicle can be precisely analyzed andthis analysis is accomplished in just a few seconds.

An exhaust gas analyzer is connected to the exhaust pipe of the vehiclewhen its rear wheels are engaged by the rollers of the dynamometer. Theexhaust gas analyzer receives samples of the exhaust gas from theexhaust pipe of the vehicle and measures the percentage of CO in theexhaust gas and thus measures the combustion efliciency of the engine. Atiming light and an engine scope are connected to the ignition system ofeach vehicle when its rear wheels are engaged by the rollers of thedynamometer. The timing light is adapted to illuminate the timing markson the engine to provide an indication of the basic timing and sparkadvance of the engine. The engine scope produces a graphicalrepresentation of waveforms generated in the ignition system of thevehicle. A fuel pressure measuring instrument and a fuel flow measuringinstrument are connected to the fuel lines of each vehicle when its rearwheels are engagd by the rollers of the dynamometer to measure the fuelpressure and rate of fuel flow in the vehicle. Because these instrumentsare adapted to be connected to each vehicle when its rear wheels areengaged by the rollers of the dynamometer, the tests with theseinstruments can be carried out very quickly while the vehicle is drivingthe rollers of the dynamometer at different speeds. The fact that thevehicles can be driven to the position where their rear wheels areengaged by the rollers of the dynamometer and then driven away from thisposition in the opposite direction, makes it possible to apply the testequipment to the vehicle quickly and easily, thus further reducing thetime required for the over-all test procedure. The time saved by thepresent invention contributes to the making possible an economicallypractical system for diagnosing almost any condition which might requirecorrection in an automotive vehicle.

Accordingly, it is a principal object of the present invention toprovide an improved system for thoroughly testing and checkingautomotive vehicles.

Another object of this invention is to reduce the time and laborrequired for thoroughly testing and checking automotive vehicles.

A further object of this invention is to make thorough testing andchecking of automotive vehicles economically practical.

A still further object of this invention is to provide for improveddiagnosis of conditions requiring correction in automotive vehicles.

A still further object of this invention is to provide for improveddiagnosis of conditions in automotive vehicles needing correction inorder to reduce repair costs.

A still further object of this invention is to provide a more accuratediagnosis of conditions needing correction in automotive vehicles.

Further objects and advantages of the present invention will becomereadily apparent as the following detailed description of the inventionunfolds, and when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 is a schematic illustration of the layout or floor plan of thediagnostic bay of the invention;

FIG. 2 is a view in perspective of the diagnostic bay with portions ofthe roof and walls broken away to reveal the interior of the bay;

FIG. 3 is a block diagram illustrating how equipment in the test bay isconnected to the engine of a vehicle under diagnosis;

FIG. 4 is a block diagram illustrating the engine scope and the sparkadvance indicator and how they are interconnected in accordance with thepresent invention;

FIG. 5 illustrates structural details of the spark advance indicator;

FIG. 6 is a block diagram illustrating the ventilation control systemfor the diagnostic bay;

FIG. 7 is a circuit diagram of the volt amp tester illustrating how itis connected to the vehicle engine;

FIG. 8 is a view in elevation of the Merrill wheel aligner, which isused in the system of the present invention;

FIG. 9 is a plan view of the Merrill wheel aligner;

FIG. 10 illustrates a circuit used in the Merrill wheel aligner formeasuring caster;

FIG. 11 illustrates the horizontal stabilizer of the present inventionused in combination with the Merrill wheel aligner;

FIG. 12 illustrates a system used for measuring wheel unbalance; and

FIGS. 13 through 15 are schematic diagrams illustrating variouspositions of a vehicle as it is processed through the diagnosticprocedure.

As illustrated in FIG. 1, the drive-through diagnostic bay has anentrance 17 and an exit 19. Automobiles to be diagnosed are driven intothe bay through the entrance 17, are tested and diagnosed, and aredriven out the exit 19. An exhaust duct 21 is provided under the floorof the drive-through bay. The duct 21 communicates with the bay througha large opening in the floor of the bay about ten feet inside of theentrance 17. This opening is covered by a grate 23, which is strongenough to support the automobiles which will be driven over it. The duct21 is connected to two vertically disposed ducts on the side wall of thedrive-through bay. The ducts 25 lead to exhaust fans, which draw airfrom the bay through the grate 23 and through the ducts 21 and 25 andexhaust the air outside. The air exhausted in this manner will carry outthe exhaust gases of the automobiles and keep the air in the test bayfresh. A Maxwell dynamometer 27 is also mounted in the floor of the testbay. The Maxwell dynamometer 27 has two pairs of rollers 29 and 31 forreceiving the right and left wheels of an automotive vehicle. Thesepairs of rollers are positioned in the floor of the test bay,approximately twentyone feet from entrance 17. The bay also has aMerrill Wheel aligner 33 which has pairs of rollers 35 and 37 located inthe floor of the test bay. The rollers 35 and 37 are positionedtwenty-five feet forward of the rollers 29 and 31 of the dynamometer 27towards the exit 19 and are spaced to receive the right and left wheelsof the automotive vehicles to be tested. The spacing between the rollersof the Maxwell dynamometer 27 and the rollers of the Merrill wheelaligner 33 is longer than the wheel bases of the automotive vehicles tobe tested so that a vehicle, after being tested with its rear wheels onthe rollers 29 and 31, moves forward to the position in which its frontwheels are on the rollers 35 and 37 of the Merrill wheel aligner.Because of this arrangement, valuable time in the testing procedure issaved. Suspended from overhead in the bay is an instrument carriage 39which can be moved by its suspension system anywhere within the dottedline 41. An instrument and control panel 67 mounted on the left handwall of the test bay is located approximately in the middle of the testbay between the Maxwell dynamometer 27 and the Merrill wheel aligner 33.Two blowers 69 are located on opposite sides of the exit 19 within thetest bay. These blowers provide a supply of fresh air to the bay and areused to maintain the temperature within the diagnostic bay at thedesired level.

The entrance 17 and the exit 19 are provided with doors which are openedand closed by positioning mechanisms. The positioning mechanism for thedoor in the entrance 17 will raise this door to its open position inresponse to a vehicle running over a treadle 43 positioned across thevehicle driveway outside the entrance 17. The positioning mechanism forthe entrance door will close the entrance door in response to a vehiclerunning over a treadle 44 positioned inside of the entrance 17 acrossthe floor of the diagnostic bay between the entrance 17 and the rollers29 and 31 of the dynamometer 27. The treadle 44 is positionedsufiiciently far enough from the entrance 17 for any vehicle which hasits front wheels on the treadle 44 to be out of the entrance 17. Theentrance 17 is provided with a photocell adapted to sense :any vehicleor other obstruction in the entrance 17 and apply a signal indicatingthe presence of such an obstruction in the entrance 17 to thepositioning mechanism for the entrance door. In response to such asignal from this photocell the positioning mechanism for the entrancedoor will hold the entrance door in its raised position even if avehicle is on the treadle 44. The positioning mechanism for the door inthe exit 19 will raise this door to its open position in response to theactuation of a switch and will lower the exit door to its closedposition in response to a vehicle running over a treadle 46 positionedacross the vehicle driveway outside the exit 19. The exit 19 is providedwith a photocell to sense any vehicle or other obstruction in the exit19 and apply a signal indicating the presence of such an obstruction tothe positioning mechanism for the exit door. In response to receivingsuch a signal from this photocell the positioning mechanism for the exitdoor will hold the exit door in its open position regardless of whethera vehicle is on the treadle 46 or not.

As will be pointed out below, some of the test equipment is mounted onthe instrument carriage 39 and some is mounted in the instrument andcontrol panel 67. The position of the instrument control panel 67 wasselected to minimize the time of making the tests with the equipmentmounted therein.

The use of the mobile instrument carriage 39 saves valuable time in thetesting procedure because it facilitates the connection of the equipmentto the vehicles. being tested. FIG. 2, which shows the interior of thetest bay in perspective, illustrates how the instrument carriage 39 issuspended to be easily movable anywherewithin the dotted line 41. Theinstrument carriage 39 is fixed to the lower end of a vertical post 70,the upper end of which is fixed to trolley 72. The trolley 72 isprovided with wheels 74 which roll on overhead tracks 76, the trolley 72being suspended by its wheels 74 from the tracks 76. The tracks 76extend perpendicular to the direction of vehicle traffic in thediagnostic bay. The tracks 76 comprise two beams which are rigidly heldtogether by cross bars 78 and the assembly of the tracks 76 and crossbars 78 is suspended by wheels 80 from tracks 82, which also comprisetwo beams. The tracks 82 extend perpendicular to the tracks 76, or inother words parallel to the direction of vehicle trafiic in thediagnostic bay. The tracks 76 are movable along the length of the tracks82 on the wheels 80. Thus the instrument carriage 39 can be movedperpendicularly to the direction of vehicle traffic in the diagnosticbay by movement of the trolley 72 along the tracks 76, or can be movedparallel to the direction of vehicle traffic by movement of the tracks76 along the tracks 82, and thus can be moved anywhere within the dottedline 41.

As shown in FIGS. 1 and 2, pendants 84, 86 and 88 hanging from theceiling are spaced along the length of the diagnostic bay. Thesependants are normally retracted and are extended when needed. Thependant 84 contains control switches to operate the dynamometer 27 andis positioned when extended to be operated by a person sitting in thedrivers seat of a vehicle in the position shown in FIG. 13, with itsfront wheels in the rollers 29 and 31 of the dynamometer 27. The pendant86 has switches to control the dynamometer 27 and the other equipmentused in conjunction with the dynamometer 27. The pendant 86 ispositioned when extended to be operated by a person in the drivers seatof a vehicle in the position shown in FIG. 14, with its back wheels onthe rollers 29 and 31 of the dynamometer 27. The pendant 88 has switchescontrolling the operation of the Merrill aligner 33 and is positioned tobe operated by a person sitting in the drivers seat of a vehicle in theposition shown in FIG. 15 with its front wheels in the rollers 35 and 37of the Merrill aligner 33. The pendants 84, 86 and 88 hang frompositioning units 90, 92 and 94, respectively, and are positionable bythese units in either an extended position where they hang low enough tobe operated by the vehicle driver or in a raised position in which theyare retracted out of the way. The positioning unit 90 will lower thependant 84 in response to actuation of a switch operated by a foottreadle 96, which is positioned in the floor of the bay between the leftwall and the dynamometer 27. The foot treadle 96 also closes a switchwhich actuates the dynamometer 27 to lower its wheel lift. Thepositioning unit 90 will raise the pendant 84in response to actuation ofa switch in the pendant 84. The positioning unit 92 will lower thependant 86 in response to actuation of a switch operated by a vehicletreadle 97 positioned across the diagnostic bay between the dynamometer27 and the Merrill wheel aligner and will raise the pendant 86 inresponse to actuation of a switch in the pendant 86. The positioningunit 94 will lower the pendant 88 in response to actuation of a switchin the pendant 86. With this arrangement, the positioning units 90, 92and 94 can be operated to lower the pendants 84, 86 and 88 only whenthey are needed and to keep them retracted out of the way at all othertimes.

FIG. 3 is a block diagram illustrating the test equipment in thediagnostic bay when it is connected up with the engine of an automotivevehicle. The engine of the vehicle is designated by the reference number98. As shown in FIG. 3, an engine scope 100 has one lead connected tothe high voltage output of the ignition coil and another lead connectedto the ignition wire of the No. 1 cylinder of the engine. The details ofthe engine scope are disclosed in the Patent No. 2,608,093, invented byAlfred E. Traver and issued on August 26, 1952, and in the copendingapplication Serial No. 172,016, entitled Analyzer for InternalCombustion Engine, filed on February 8, 1962, and invented by Alfred E.Traver. As disclosed in the Traver patent the engine scopesimultaneously depicts a plurality of vertically separated horizontalWave-forms, one for each cylinder of the engine and synchronized withthe functioning of such cylinder. FIG. 4 is a block diagram whichillustrates how the engine scope is used in the present invention. As inthe Traver patent, the scope leads are clipped over the insulation ofthe wires of the engine to be capacitively connected thereto rather thanbeing directly connected. In FIG. 4 these leads are designated by thereference numbers 102 and 104. The leads designated 102 and 104 feed thesignal voltages generated at the high voltage output of the ignitioncoil and at the ignition wire of the No. 1 cylinder to a synchronizationand sweep generating circuit 106 in the engine scope 100. The circuit106, in response to the applied signals, feeds appropriate waveforms tothe vertical and horizontal amplifiers of an oscilloscope 108, as isdisclosed in the Traver patent, in order to produce the verticallyseparated horizontal traces, each synchronized with a differentcylinder. In order to depict the waveform of the high voltage output ofthe ignition coil for each cylinder, the lead 102, which applies thesignal from the ignition coil to the synchronization and sweepgenerating circuit 106, is also connected to the input of the verticalamplifier of the oscilloscope 108. With this arrangement, theoscilloscope shows the voltage waveform at the output of the ignitioncoil for each cylinder as it fires and immediately thereafter. Fromthese waveforms a diagnostician can determine the dwell for eachcylinder; he can determine whether the spark plug and the ignition wireare in satisfactory condition for each cylinder; he can determinewhether the coil, the points and the condenser are in satisfactorycondition; and he can determine whether the distributor lobes, thedistributor drive and the distributor bearings are in satisfactorycondition.

The interconnection of the synchronization circuitry 106 and theoscilloscope 108 is made internally in the engine scope, and thediagnostician only has to make two connections in order to connect theengine scope to the engine of the vehicle being tested.

As shown in FIG. 3, the movable pole of a switch 110 is connected to theprimary winding of the ignition coils of the engine 98. In one positionthe switch 110 connects the primary winding to ground, shorting it out,and in the other position the switch 110 connects the ignition coilprimary to the input of an engine tachometer 112. When the switch 110connects the primary winding of the ignition coil to the tachometer 112,the tachometer 112, in response to the pulses generated in the ignitioncoil by the action of the breaker points, produces a visual indicationof the revolutions per minute of the engine and also produces anelectrical output signal representing this value. The electrical signalproduced by the engine tachometer 112 is fed to a strip chart recorder114. A spark advance indicator 116 is connected to the engine scope 100to produce a visual display of the basic timing of the engine andindicate the total spark advance.

FIG. 4 includes a block diagram of the spark advance indicator circuitand illustrates how it is interconnected with the engine scope. As shownin FIG. 4, the signal from the No. 1 cylinder ignition wire on lead 104is applied to a timing circuit 118 of the spark advance indicator 116.In response to each pulse on lead 104, the timing circuit 118 triggersan energizing circuit 120', which in response thereto energizes a flashtube 122. A pulse will occur on lead 104 simultaneously with each firingof the No. 1 cylinder. Thus, each time the spark plug of the No. 1cylinder fires, the flash tube 122 will be energized. The timing circuit118 Will either trigger the energizing circuit 120 immediately inresponse to each pulse on lead 104 or will trigger it after a time delaywhich is continuously and selectively variable by means of a control124. The timing circuit 118 also applies a signal to an indicator 126,which provides a visual indica tion of the amount of delay provided bythe timing circuit 118. Because the spark advance indicator 116 receivesits signal from the lead 104, it does not have to be separatelyconnected to the engine 98, and the diagnostician, upon connecting theleads 102 and 104 to the engine 98, has connected both the engine scope100 and the spark advance indicator 116 to the engine, thus savingvaluable time.

FIG. 5 illustrates the structure of the spark advance indicator. Asshown in FIG. 5, the spark advance indicator comprises a housing 128 anda remote flash unit 130 connected to the housing 128 by a cable 132. Thetiming circuit 118, the energizing circuit 120, and the indicator 126are mounted in the housing 128. The remote flash unit 130 includes theflash tube 122 and the control 124. The interconnections between theflash tube 122 and the energizing circuit 120 and between the control124 and the timing circuit 118 are through the cable 132. The flash tube122, and the control 124 are mounted in a barrel casing 134 whichfunctions as a handle. The control 124 is manually operated by means ofa knob 136. By adjusting the angular position of the knob 136, the delayprovided by the timing circuit 118 can be selected.

In operation the diagnositician illuminates the timing marks in theengine 98 with the flash tube 122. This illumination will cause thetiming marks to apparently stop in stroboscopic illusion at the positionthey are in each time the flash tube 122 is energized. The timing markscooperate with a reference mark to indicate the position of the pistonin the No. 1 cylinder relative to top dead center when the flash tube122 is energized. In order to read basic timing, which is the positionof the piston in the No. 1 cylinder relative to top dead center when itfires with no distributor induced spark advance, or in other words atidle speed, the diagnostician by means of the knob 136 selects no delayby the timing circuit 118 and the engine is operated at idle speed. Thediagnostician then illuminates the timing marks with the flash tube andobserves the indication, which will be the basic timing of the engine.In order to observe the spark advance at a particular speed, the engineis operated at the speed of interest and the knob 136 is adjusted untilthe indication by the timing marks is the same as that of basic timing.The delay indicated by the indicator 126 as being provided by the timingcircuit 118 will be the spark advance at this particular speed. Becausethe control 124 is provided with the remote flash unit 130 instead of onthe housing 128, the diagnostician taking the spark advance reading isable to obtain this reading in a much shorter time.

The Maxwell dynamometer 27 has a tachometer 138 producing a signalproportional to the speed at which the rollers 29 are driven, atachometer 140 producing a signal proportional to the speed at which therollers 31 are driven, and a transducer 142 which produces an outputsignal proportional to the torque being absorbed or transmitted by themotor of the dynamometer 27. The dynamometer 27 has a third tachometer143 which like the tachometer 138 produces an output signal proportionalto the speed at which the rollers 29 are driven. The output signalproduced by the tachometer 143, which will be proportional to the wheelspeed of the vehicle, is applied to the strip chart recorder 114. Thestrip chart recorder 114 thus receives a signal proportional to thewheel speed of the vehicle and a signal proportional to the engine speedof the vehicle. The strip chart recorder 114, when it is actuated,produces a chart with two traces, one of which represents the enginer.p.m. vs. time and the other of which represents wheel speed vs. timeover the same period. From the recording done by the strip chartrecorder 114, the engine r.p.m. can be compared with the rear wheelspeed and the operation of the vehicle transmission can be analyzed. Theoutput signal from the tachometer 143 is also fed to a dynamometer liftout out circuit 145, which in response to receiving a signal from thetachometer 143 prevents the dynamometer 27 from raising its wheel lift.This circuit prevents accidental raising of the dynamometer wheel liftwhen the wheels of a vehicle are turning on the rollers of thedynamometer 27. The output signal of the tachometers 138 and 140 areapplied to averaging circuit 144, which produces an output signalproportional to the average of the output signals of the tachometers 138and 140 and representing the average wheel speed of the vehicle. Noaveraging is needed in the strip chart recording operation because inthis operation both rear wheels will be driven at approximately the samespeed. The output signal from the transducer 142 representing the torqueabsorbed by the dynamometer motor and the output signal of the averagingcircuit 144, which represents the wheel speed of the vehicle, are fed toa horsepower meter 146. In response to these signals the horsepowermeter 146 produces a visual indication of the horsepower transmittedbetween the vehicle wheels and the dynamometer 27. The output signalfrom the tachometer 138 and the output signal of the tachometerrepresenting the right and left wheel speeds are fed to a balance meter148, which provides a visual indication of the difference in the speedsrepresented by the output signals of the tachometers 138 and 140. Thusthe balance meter 148 produces a signal representing the difference inspeeds of the right and left vehicle wheels. This balance meter 148connected in this manner can be used to provide an indication of thebraking balance between the wheels, the balance of horsepowertransmitted to the rear wheels, and a balance of the parasitichorsepower absorbed by the wheels. The output signal of the averagingcircuit 144 is also fed to an m.p.h. meter 150, which produces a visualindication of the speed represented by the output signal of theaveraging circuit 144 and thus a visual indication of the vehicle wheelspeed. The output signal of the averaging circuit 144 is also fed to arate meter 151, which by means of a resistor and capacitor networkmeasures and indicates the rate of change of the output signal of theaveraging circuit 144. The indication of the rate meter 151 willtherefore be a measure of the acceleration of the wheels of the vehicle.

The output signal from the engine tachometer 112 is also fed to a fanand blower control 152, which controls the rate that air is exhaustedfrom and fresh air is brought into the bay. The block diagram in FIG. 6illustrates how the fan and blower control 52 operates. The system isprovided with two exhaust fans which exhaust air from the test baythrough the ducts 21 and 25. One of the exhaust fans runs all of thetime and the other, designated by the reference number 154 in FIG. 6, iscontrolled automatically in response to the output signal from theengine tachometer 112. When the engine tachometer 112 is not producingan output signal, the fan and blower control 152, in response to thiszero output signal of the engine tachometer 112, runs the intake blowers69 at half speed and maintains the exhaust fan 154 shut ofl. When theengine tachometer 112 produces an output signal, the fan and blowercontrol 152, in response to this signal, will operate the intake blowers69 at full speed and will maintain the exhaust fan 154 turned on. Inthis manner the exhaust fan 154 is run only when the engine of thevehicle under diagnosis is being run under test with the enginetachometer 112. During the other parts of the testing when the engine ofthe vehicle is not running under test and less air exhaustion is needed,the fan 154 is automatically shut off. The intake blowers 69 areautomatically run at full speed only when the exhaust fan 154 is beingoperated, thus providing an increased supply of temperature-conditionedair when the exhaust fan 154 is running. Thus the amount of air beingexhausted from the diagnostic bay and the amount of fresh aid beingbrought into the diagnostic bay are automatically increased when theengine of a vehicle is being run under test in the diagnostic bay.

As shown in FIG. 3, a tube 156 is connected to sample exhaust from theexhaust pipe of the engine 98. The tube 156 feeds a sample of theexhaust gas to an exhaust analyzer 158, which measures the percentage ofCO in the exhaust gas and produces a visual indication of thismeasurement. This indication reflects the combustion efficiency of theengine 98. The vacuum gauge 160 is connected to measure the vacuum atthe intake manifold and produces a visual indication of thismeasurement. A volt amp tester 162 is connected to measure the generatorcurrent and to measure the voltage between the regulator batteryterminal and ground. The volt amp tester 162 is used to provide anindication of the regulated generator output amperage and voltage andalso an indication of the amperage when the cutout relay of theregulator opens and the voltage at which it closes. It is also used toprovide an indication of the cranking battery voltage. The volt amptester of the present invention requires only three leads instead vofthe usual five. Because of this fact, the diagnostician 'has to connectonly three leads between the volt amp tester and the engine, and as aresult valuable time is saved. FIG. 7 is a circuit diagram illustratingthe circuit of the volt amp tester and how it is connected to theelectrical system of the vehicle under diagnosis. In FIG. 7 the vehiclebattery is designated by the reference number 164, the vehicle generatorby the reference number 166, and the regulator by the reference number168. In a conventional vehicle electrical system one side of the batteryis grounded and the other side of the battery is connected to oneterminal of the generator through the regulator, the other terminal ofthe generator being grounded. The junction between the battery and theregulator is connected to the vehicle electrical circuit including theignition switch, the starter motor, the ignition coil, the lights, horn,etc. In FIG. 7 the lead which in the electrical system connects thevehicle circuit to the junction between the battery 164 and theregulator 168 is designated by the reference number 170. The volt amptester 162 comprises a voltmeter 172 and an ammeter 174. One terminal ofthe voltmeter 172 is connected to one terminal of the ammeter internallyin the volt amp tester. The three leads of the volt amp tester aredesignated by the reference numbers 176, 178 and 180. The lead 178 isconnected to the junction between the voltmeter 172 and the ammeter 174.The lead 176 is connected to the other terminal of the voltmeter 172 andthe lead 180 is connected to the other terminal of the ammeter 174. Aswitch 181 and a load resistor 183 are connected in series across thevoltmeter 172 between the lead 176 and the lead 178.

As shown in FIG. 7, when the volt amp tester is connected to theelectrical system of the vehicle, the lead running between the lead 170and the regulator 168 is disconnected from the terminal ofthe regulator,which is designated 182, and connected to the lead 180. The lead 178 isconnected to the terminal 182 and the lead 176 is connected to theground. In this manner when the switch 181 is open the electrical systemof the vehicle is connected to function normally with the ammeter 174connected to measure the current flowing between the regulator 168 andthe lead 170, or in other words the current of the generator 166 and thevoltmeter 172 conected to measure the voltage between the terminal 182and ground. When the switch 181 is closed it imposes a known loadprovided by the resistor 183 on the generator so that the regulatedoutput of the generator can be checked under a known load.

As shown in FIG. 3, a flow meter 184 is connected by means of fuel lines186 and 188 between the fuel pump and the carburetor to measure the rateof fuel flow. A fuel pressure gauge 190 is connected to the fuel linebetween the fuel pump and the carburetor to measure the fuel pumppressure. When the fuel flow meter 184 is connected up with the fuelsystem, it, together with the fuel lines 186 and 188, is connected inseries with the regular fuel line between the fuel pump and thecarburetor. To eliminate the labor of separately connecting the fuelpressure gauge 190 to :the engine fuel line, the fuel pressure gauge 190is conected permanently to the fuel line 186. Thus once the flow meter184 is connected in the fuel system of the vehicle, the pressure gauge190 will also be connected to measure the final pressure between thefuel pump and the carburetor.

The engine scope 100, the spark advance indicator 116, the volt amptester 162, the manifold vacuum gauge 160, the fuel flow meter 184 andthe fuel pressure gauge are all mounted in the instrument carriage 39,which is suspended from overhead to be freely movable within the dashedline 41 as described above, so that these instruments may be easilyconnected to the vehicle to be tested. The instruments mounted on theinstrument carriage 39 all retract their leads into the carriage 39 whenthe leads are not in use. The fan control 152 and the strip chartrecorder 114, the balance meter 148, the horsepower meter 146, them.p.h. meter 150, the rate meter 151, the engine tachometer 112, and theexhaust gas analyzer 158 are mounted in the instrument and control panel67.

The above described instruments will be connected to the engine of thevehicle in the manner described when the vehicle is being tested on theMaxwell dynamometer 27. After being tested on the Maxwell dynamometer 27the vehicle is then advanced until its front wheels fall into therollers 35 and 37 of the Merrill aligner 33. The Merrill aligner 33provides a visual indication of the caster and camber of the left wheel,a visual indication of the caster and camber of the right wheel, and avisual indication of the total toe of the front wheels. In the Merrillaligner the rollers 35 and 37 are mounted on carriages. When the frontwheels of the vehicle under diagnosis are on the rollers 35 and 37, therollers 35 and 37 are driven at a constant speed by electric motors andin turn the rollers 35 and 37 drive the front wheels of the vehicle.Means are provided in the carriages mounting the rollers 35 and 37 toposition the rollers 35 and 37 so that the axes of the rollers 35 areparallel with the axis of the right front wheel of the vehicle and theaxes of the rollers 37 are parallel with the left front wheel of thevehicle. FIGS. 8 and 9 show the details of the carriage mounting therollers 37 and illustrate how the carn'age aligns the axes of therollers 37 parallel with the axis of the left front wheel. The carriagemounting the rollers 35 aligns the axes of the rollers 35 with the axisof the right front wheel in the same manner that the carriage mountingthe rollers 37 aligns the rollers 37. As shown in FIGS. 8 and 9, therollers 37 are driven by electric motor 192 which is also mounted on thecarriage. The carriage comprises a base 194, on which the electric motor192 is mounted, and an upper bracket 196 which is pivotable with respectto the base 194 and on which the rollers 37 are rotatably mounted. Thebracket 196 pivots on the base 194 about a pivot point designated 198and the amount that the bracket 196 is pivoted with respect to the base194 is controlled by means of a hydraulic servo unit 200. The base 194is mounted on rollers 202 and is pivotable about a fixed vertical axis204 on the rollers 202. When the rollers 37 are driving the front wheelof the vehicle the base 194 will pivot about the vertical axis 204 dueto forces exerted on the rollers 37 until the horizontal components ofthe axes of the rollers 37 are parallel with the horizontal component ofthe axis of the vehicle wheel. However, due to the camber of the wheel,the axes of the rollers 37 will still not necessarily be parallel withthe axis of the wheel. The hydraulic servo unit 200 will pivot thebracket 196 with respect to the base 194 until the axes of the rollers37 are parallel with the axis of the vehicle wheel. To provide thecontrol for the hydraulic servo unit 200 to achieve this result, therollers 37 are axially slidable short distances on their axles 206. Whenthe rollers 37 are driving the vehicle wheel and the axis of the vehiclewheel due to its camber is not aligned with the axes of the rollers 37,the vehicle wheel will exert forces on the rollers 37 sliding them toone side or the other, depending upon the direction of the misalignment.The rollers 37, on being slid to one side, will actuate a microswitch,and in response to the actuation of this microswitch the hydraulic servounit 200 will be energized to change the angular position of the bracket196 with respect to the base 194 in a direction to eliminate themisalignment of the axis of the vehicle wheel with the axes of therollers 37. Similarly, when the rollers 37 are slid to the other side inresponse to the misalignment being in the opposite direction, therollers 37 will actuate a microswitch, in response to which thehydraulic servo unit 200 will change the angular position of the bracket196 with respect to the base 194 in the opposite direction until themisalignment is eliminated. In this manner the axes of the rollers 37are made parallel with the axis of the vehicle wheel. A potentiometer208 produces an output signal representing the angular position of thebase 194 with respect to the fixed vertical axis 204. When the rollers37 have been aligned with the vehicle wheel, the output signal of thepotentiometer 208 will therefore represent the toe of the vehicle wheel.A potentiometer 210 produces an output signal representing the angularposition of the bracket 196 with respect to the base 194. When therollers 37 have been aligned with the vehicle wheel, the output signalof the potentiometer 210 will represent the camber of the vehicle wheel.The carriage supporting the rollers 35 produces output signalsrepresenting toe and camber in the same manner. To obtain the caster ofa vehicle wheel on the rollers 37, the Merrill aligner uses the circuitillustrated in FIG. 10. While the rollers 37 drive the vehicle wheelthereon and the rollers are maintained aligned therewith, the vehiclewheels are turned 7%. to the right. The output signal voltage of thepotentiometer 210 when the wheels are turned 7 /2 to the right is storedin a storage means 207. The vehicle wheels are then turned 7 /2 to theleft and the output signal voltage of the potentiometer 210 is stored ina storage means 209. A differential amplifier 211 then amplifies thedifference between the signal voltage stored in the storage means 207and that stored in the storage means 209 and applies a signalproportional to this difference to a meter 213, which provides anindication of this signal. When these operations have been carried out,the output signal of the differential amplifier 211 will be proportionalto and the meter 213 will indicate the caster of the wheel in therollers 37. An identical circuit is provided for the rollers 35 tomeasure the caster of the Wheel in these rollers in the same manner. Thecaster measuring operations are performed simultaneously so that thewheels only need to be turned to the right and to the left once toobtain the caster measurement for both wheels.

When the vehicle is being tested on the Merrill aligner in this manner,it is necessary to hold the front of the vehicle in place so that itdoes not slide off the rollers to the right or the left. The device forproviding this holding is called a horizontal stabilizer. The horizontalstabilizer of the present invention, which illustrated in FIG. 11,permits it to be quickly and easily applied to the vehicle withouthaving to actually be bolted thereto, thus saving valuable time in thediagnostic procedure. As shown in FIG. 11, the horizontal stabilizercomprises a pair of braces 212 which move transversely across thedrive-through bay driven by hydraulic cylinders 215, on a track 214recessed beneath the floor of the drive-through bay. Carriages 217 aremounted on the braces 212 to have a limited horizontal movement withrespect to the braces 212 transverse to the direction that the bracesthemselves are moveable. The carriages 21.7 have rollers which engagethe braces to provide the limited motion for the carriages. Springs holdthe carriages 217 normally in the center of their range of movement. Thecarriages 217 have mounted thereon rubber cushions 216 and arepositioned to engage the wrap-around part of a vehicle bumper with theserubber cushions when the front wheels of the vehicle are lodged in therollers 35 and 37 of the Merrill aligner 33. When the front wheels ofthe vehicle have been so positioned, the braces 212 are moved inwardlyby the hydraulic cylinders 215 toward the vehicle on the track. 214until the rubber cushions 216 engage the wrap-around part of the bumperof the vehicle and firmly hold the front of the vehicle in position.Because the carriages 217, on which the rubber cushions are mounted,have a limited horizontal movement with respect to the braces 212, thebraces 212 engaging the vehicle and holding the vehicle on the rollers35 and 37 will not interfere with the caster reading operation. Themoveable carriages permit the pivoting of the vehicle frame that occurswhen the front wheels are turned 7 /2 to the right and left during thecaster reading procedure while still preventing the vehicle frame frommoving sideways.

When the vehicle is driven off the rollers 35 and 37 after the alignmenthas been checked, the vehicle wheels exert force on the carriagesmounting the rollers 35 and 37 tending to move these carriages forward.This action automatically activates table locks which hold the carriagesin position and prevent them from being banged about as vehicle wheelspass over them. A switch is provided in the pendant 88 to release thetable locks.

FIG. 12 illustrates the system for testing the unbalance of a frontwheel of the vehicle. The system as shown in FIG. 12 makes use of avibration detector 218, which is attached to the suspension assembly ofthe front wheel being tested, and preferably on the lower control arm ofthis assembly. As shown in FIG. 12, the output signal of the vibrationdetector is fed through a low pass filter 220 and then to meter 222which indicates the amplitude of the filtered signal. When the wheel isrotated, the vibration detector 218 mounted on the wheel suspensionassembly will produce an output signal which varies in' accordance withthe amount of wheel unbalance. This output signal will be at a frequencyequal to the revolutions per second that the wheel is rotated. The lowpass filter 220 filters out signals and noise in the output signal ofthe vibration detector above the frequency of the signal caused by thewheel unbalance and serves to eliminate these extraneous signals. Therewill be no substantial extraneous signals or noise in the output of thevibration detector 218 below the frequency of the signal caused by wheelunbalance. The measurement of the wheel unbalance of the front wheels ofthe vehicle is taken when the front wheels of the vehicle are positionedon the rollers 29 and 31 of the dynamometer and these rollers are usedto impart the rotation to the wheels required for the unbalancemeasurement. A separate system such as that shown in FIG. 12 isconnected to the suspension assembly of each front wheel in the testprocedure so that the unbalance of both front wheels can be measuredsimultaneously.

Two diagnosticians are employed at the diagnostic center to carry outthe tests and diagnoses on the automotive vehicles. The procedure oftesting and diagnosis on each vehicle is planned to take the leastpossible amount of time per vehicle being tested so as to make thecomplete testing and diagnosis of all manner of malfunctionings ofautomotive vehicles economically practical. To achieve this purpose theschedule of testing procedure eliminates lost or wasted time by thediagnosticians.

T o facilitate the description of the procedure, the diagnosticians aredesignated A and B. While diagnostician B is busy with the precedingvehicle, diagnostician A drives the next vehicle up to the entrance 17.When the vehicle passes over the treadle 43, the entrance door raisesautomatically and diagnostician A drives the vehicle through theentrance 17 to the first testing station in which the vehicle is in theposition shown in Fig. 13. In proceeding to this testing station, thevehicle passes over the treadle 44 and this action causes the entrancedoor to close again automatically. When the vehicle is positioned at thefirst testing station, the front wheels of the vehicle will bepositioned between the rollers of the dynamometer. At this time the liftfor the dynamometer will be in its raised position so the front wheelsof the vehicle will be resting on the dynamometer lift. The

13 diagnostician A then gets out of the vehicle and checks the tires ofthe vehicle and adjusts their pressure. At this time diagnostician Aalso attaches the vibration detectors of the wheel unbalance detectionsystems illustrated in FIG. 12 to the front wheel suspension assemblies.Next the diagnostician A checks the transmission fluid level and obtainsa sample of the fluid for purpose of analysis. Diagnostician A thenchecks the radiator, the engine oil level, the fan belt, the hoses, thereat riser, the headlights and other lights on the vehicle, the parkbrake, the horn, the wipers, the turn signals, checks for audibleexhaust leakage, and measures the battery capacity. A Hoppy Lev-L-Litemanufactured by Hopkins Manufacturing Company of Emporia, Kansas, isused to check the alignment of the headlights. Meanwhile during thistime diagnostician B has driven the preceding car out of the diagnosticbay from exit 19 and discusses the diagnosis on the preceding vehiclewith the owner. After performing the checks described above,diagnostician A actuates the foot treadle 96. This action causes thedynamometer to lower its wheel left and the positioning unit 90 to lowerthe pendant 84 to the extended position. Diagnostician A gets into thevehicle and then energizes the dynamometer motor so that the rollers 29and 31 drive the front wheels of the vehicle. Diagnostician A controlsthe operation of the dynamometer when the vehicle is in the positionshown in FIG. 13 by means of switches on the control pendant 84, whichwill be in its extended position and hang next to the drivers windowwhen the vehicle is in this position. Thus the driver can control theoperation of the dnyamometer from the drivers seat, and valuable time issaved. While the rollers 29 and 31 are driving the front wheels, thehorsepower required to drive the front wheels is read by thediagnostician A on the horsepower meter 146 and recorded. Thishorsepower is referred to as parasitic horsepower. The diagnostician Aalso reads the balance meter 148 and records this reading. This readingprovides the parasitic horsepower balance of the front wheels. At thistime he also reads and records the amount of front wheel unbalanceindicated by the meters 222 in the wheel unbalance detection systemsattached to the front wheel suspension assemblies. Then while thedynamometer 27 is driving the front wheels, the diagnostician A appliesthe brakes, and while the brakes are applied he reads the horsepowermeter 146. This gives a reading of the efliciency of the front wheelbrakes. While the breakes are applied the diagnostician A also reads thebalance meter 148 and records this reading, which is an indication ofthe balance of the front wheel brakes. While the parasitic horse powerand brake tests on the front wheels are being carried out bydiagnostician A, diagnostician B enters the diagnostic bay and performsan analysis on the transmission fluid sample obtained from the vehicleby diagnostician A. This analysis of the transmission fluid determinesthe degree of oxidation of the transmission fluid. If the oxidation ofthe transmission fluid is too high, then the fluid should be changed toavoid damaging the vehicle transmission. The tests for the oxidation ofthe fluid is fully described in a copending application entitled Methodfor Estimating Quickly the Neutralization Number for Automatictransmission Fluid, Serial No. 241,168, invented by Charles FrederickFeaesley and Fernando Albert Pellicciotti and filed on the same day asthe present application. When diagnostician B has completed the analysisof the transmission fluid and diagnostician A has completed the braketest on the front wheels of the vehicle, diagnostician B disconnects thevibration detectors from the front wheel suspension assemblies.Diagnostician A then stops the dynamometer motor and actuates the wheellift between the rollers 29 and 31 by means of control switches on thependant 84. The switch that actuates the wheel lift also actuates thepositioning unit 90, which then retracts the pendant 84 to its raisedposition. 1 The wheel lift raises the front wheels out from between therollers 29 and 31 so that the vehicle can be driven forward.Diagnostician A then drives the vehicle forward and runs over thetreadle 97, which action causes the dynamometer 27 to lower its lift andthe positioning unit 92 to lower the pendant 86 to its extendedposition. Diagnostician A drives the vehicle forward until the rearwheels of the vehicle are on the rollers 29 and 31 of the dynamometer27. At this time the vehicle will be in the position shown in FIG. 14.Diagnostician B then walks to the front of the car and sets checks onthe front wheels to hold the vehicle rear wheels on the rollers 29 and31. Diagnostician B then opens the hood of the vehicle, removes the aircleaner and connects the fuel flow meter 184 and the fuel pressure meter190 into the fuel system by means of the fuel lines 186 and 188, asdescribed above. 'The fuel flow meter 184 will then be connected betweenthe fuel pump and the carburetor, and the fuel pressure meter 190 willbe connected to measure the pressure in the fuel line between the fuelpump and the carburetor. While diagnostician B is connecting up the fuelflow meter 184 and the fuel pressure meter 190, diagnostician A gets outof the vehicle and inserts the combustion efiiciency sample hose 156 inthe tailpipe of the vehicle and then connects the engine scope to thehigh voltage output of the ignition coil and the ignition wire of theNo. 1 cylinder, as described above. Also while the diagnostician B isconnecting up the fuel flow meter 184 and the fuel pressure meter 190,the diagnostician A connects the vacuum gauge 160 to the enginemanifold. Diagnostician B then connects the volt amp tester 162 to theengine. Diagnostician B then connects the switch to the primary of theignition coil and throws the switch to the position in which it shortsout the primary. Meanwhile, diagnostician A gets back into the driversseat. Diagnostician A then engages the engine starter, and diagnosticianB reads and records the cranking voltage which will be indicated by thevoltmeter of the volt amp tester. If the cranking voltage is not withinspecification limits, diagnostician B then reads and records the amperedraw, which will be indicated by the ammeter of the volt amp tester whenthe primary of the ignition coil is shorted out and the starter switchis engaged. Diagnostician B then positions the switch 110 to theposition in which it connects the engine tachometer to the primary ofthe ignition coil. Diagnostician A then starts the vehicle engine andlets it idle. While the engine is idling, diagnostician A reads andrecords the engine r.p.m. shown on the engine tachometer 112, thusobtaining an indication of the engine idle speed. Also while the engineis idling, diagnostician A reads the vacuum gauge to obtain the manifoldvacuum at idle. The reading of the exhaust gas analyzer 158 is read andrecorded while the engine is idling by the diagnostician A to provide areading of the combustion efficiency at idle. Diagnostician B, while theengine is idling, reads and records the basic timing indicated by thespark advance indicator 116. Di agnostician A then increases the enginespeed gradually to 1200 r.p.m. as indicated by the engine tachometer112. While the engine speed is being gradually increased in this manner,diagnostician B reads the regulator cutout closing voltage, which willbe indicated by the voltmeter of the volt-amp tester 162. DiagnosticianA then holds the engine speed at 1200 r.p.m. as indicated by the enginetachometer 112, and reads and records the exhaust analyzer 158, whichwill indicate combustion efliciency at 1200 r.p.m. Diagnostician B,while the engine is being held at 1200 r.p.m., closes the switch 181 onthe volt amp tester 162 and reads the regulated voltage output of thegenerator indicated on the volt amp tester 162. Diagnostician B thenopens the switch 181 and diagnostician A opens the throttle rapidly andreturns to 1200 r.p.m. and at the same time reads and records theindication of the exhaust analyzer 158 to obtain the carburetoraccelerating pump efficiency. Meanwhile the diagnostician B synchronizesthe engine scope 100, if necessary, and

makes a preliminary reading of the waveforms on the engine scope.Diagnostician A then increases the engine speed to 2500 rpm. and holdsthe engine speed at this value as indicated by the engine tachometer112. While the engine speed is held at 2500 r.p.m. the combustionefficiency is read and recorded from the exhaust gas analyzer 158.Diagnostician B, while the engine speed is being held at 2500 r.p.m.,reads and records the maximum spark advance indicated by the sparkadvance indicator 116. Diagnostician A then returns the engine speed toidle gradually, and while this gradual return to idle is being carriedout by diagnostician A, diagnostician B reads and records the regulatorcutout opening amperes indicated by the volt amp tester 162.Diagnostician A then after the engine speed reaches idle reads andrecords the fuel pump pressure meter 190. Diagnostician A next startsthe strip chart recorder 114 by actuating a switch in the pendant 86,which will be in its extended position and hang next to the driverswindow when the vehicle is in the position shown in FIG. 14.Diagnostician A then accelerates the car through all gears whilediagnostician B observes the waveforms on the engine scope 100. Thestrip chart recorder will shut itself off automatically after apredetermined time interval. The time interval will be long enough toexceed the duration of the acceleration of the vehicle through all ofits forward speeds so that the chart of the engine and wheel speedversus time covers the full cycle of acceleration. Diagnostician A thenadjusts the engine speed until the miles per hour meter 150 indicatesthat the vehicle is driving the dynamometer 27 at 50 m.p.h.Diagnostician A then observes the speedometer and records the ditferencebetween the speed indicated by the speedometer and that indicated by themiles per hour meter 150, to obtain a calibration of the speedometer.Then while the engine is driving the dynamometer rollers at 50 mph. asindicated by the miles per hour meter 150, the diagnostician A reads thefuel flow indicated by the flow meter 184. This indication of the fuelflow meter 184 is then used to determine the miles per gallon obtainedby the vehicle at 50 m.p.h. Diagnostician A then opens the throttle ofthe vehicle to wide open. While the vehicle is acceleratingdiagnostician A reads the rate meter 151 to obtain an indication of theacceleration of the vehicle. Diagnostician A then returns the vehicle to50 mph, energizes the dynamometer motor by means of a switch at pendant86 and opens the throttle to wide open. While the throttle is at wideopen, diagnostician A observes the maximum horsepower generated by thevehicle as indicated by the horsepower meter 146. Also while thethrottle is wide open the diagnostician A reads and records the fuelpressure indicated by the fuel pressure meter 190. During this timediagnostician B continues to observe the waveforms on the engine scope.Diagnostician A then closes the throttle and places the transmission ofthe vehicle in neutral. At this time diagnostician B records theconclusions reached from observation of the waveforms depicted by theengine scope. He records the dwell and whether or not the firing voltageis satisfactory and whether or not the condition of the points, ignitionwires, the coil, the condenser, and the distributor drive, lobes andbearings are satisfactory. Diagnostician A then observes the parasitichorsepower for the rear wheels indicated by the horsepower meter 146 andobserves the parasitic horsepower balance for the rear wheels indicatedby the balance meter 148. Next diagnostician A applies the brakes andobserves the reading of the horsepower meter 146 to determine theefficiency of the rear brakes. While the brakes are applied,diagnostician A also observes the reading of the balance meter 148 todetermine the balance of the rear brakes. While the car is being putthrough these paces, the diagnostician B disconnects all the equipmentfrom the vehicle except the fuel flow meter, fuel pressure meter, andthe com bustion efliciency analyzer. Diagnostician A then turns off thedynamometer motor and stops the rear Wheels with the vehicle brakes.Diagnostician A then turns off the vehicle engine and records thepertinent data on the data sheet. While diagnostician A is performingthese operations, diagnostician B disconnects the fuel flow meter 184and the fuel pressure meter from the fuel system and reconnects theoriginal fuel lines of the vehicle. Diagnostician A then again startsthe engine and diagnostician B observes the fuel system to see if thereare any fuel leaks. Diagnostician B then installs the air cleaner andtears the recorded chart off from the strip chart recorder 114.Diagnostician B then gives this strip chart to diagnostician A anddiagnostician A attaches the strip chart to the data sheet.Diagnostician B then removes the combustion efiiciency sample hose 156of the exhaust gas analyzer 158 from the exhaust pipe and thendiagnostician A actuates the dynamometer lift by means of a controlswitch on the pendant 86 to raise the rear wheels of the vehicle outfrom between the rollers 29 and 31. The operation of this control switchalso actuates the positioning unit 94, which then lowers the pendant 88to its extended position. Diagnostician A then drives the vehicleforward until the front wheels are in the rollers 35 and 37 of theMerrill aligner 33, as shown in FIG. 15. Diagnostician B then leaves thediagnostic bay to pick up the next vehicle to be diagnosed.Diagnostician A then releases the table locks for the Merrill alignerand actuates the horizontal stabilizer for the Merrill aligner by meansof switches on the pendant 88. The hydraulic pistons of the horizontalstabilizer then drive the braces 212 inwardly until the rubber cushionsengage the wrap-around part of the bumper of the vehicle and hold thevehicle in place. Diagnostician A then checks the wheel alignment on theMerrill aligner 33 by reading the amount of toe, camber and caster.Diagnostician A operates the Merrill aligner by means of switches on thependant 88 to take these readings entirely while sitting in the driver'sseat of the vehicle. After these readings are taken, diagnostician Aactuates a switch on the pendant 88, which switch actuates thehorizontal stabilizer to retract the braces 212 from the vehicle,actuates the positioning unit 94 to raise the pendant 88 to itsretracted position, and actuates the positioning mechanism for the exitdoor to raise the exit door. Diagnostician A then drives the vehicle outof the diagnostic bay through the exit 19 and passes over the treadle46. In response to the vehicle passing over the treadle 46, thepositioning mechanism for the exit door lowers the exit door to itsclosed position. Diagnostician A then enters the customer lounge todiscuss the results of the analysis with the customer. Whilediagnostician A is performing the wheel balance and wheel alignmentchecks and discussing the results of the analysis with the oils tomer,diagnostician B has already started the test procedure on the nextvehicle. On the next vehicle, diagnostician B performs the duties thatwere performed by diagnostician A on the preceding vehicle, and viceversa.

Many modifications may be made to the above described specificembodiment of the invention without departing from the spiritand scopeof the invention, which is defined in the appended claims.

What is claimed is:

1. In a system provided for rapid, efiicient, uniform diagnoses of aplurality of in line closely following, independently, intermittentlymoving automotive road vehicles to determine and identify deficientcharacteristics of each thereof by testing each said vehicle at each ofa plurality of stations as said vehicle is rolled in normal manner toand beyond each said station in proceeding to a point of exit, wherebyeach vehicle will be diagnosed to substantially the same and overallextent sufficient to provide a master record of its faults and therebypermit its repair and correction as desired subsequent to diagnosis,comprising a diagnostic passageway having an entrance and stations alongsaid passageway thereby adapting same to an exit, constructional meansspacing said plurality of receive said line of vehicles with one vehicleat at least each of a majority of said stations with working spacebetween said respective vehicles, means determining the width of saidpassageway at least sufliciently wide to permit lengthwise transit ofsaid line of vehicles and sufiiciently narrow to require substantiallylengthwise transit of each successive vehicle in said line through eachsuccessive station, diagnostic test equipment operative at each saidstation adapted for a diiferent diagnostic test sequentially on eachrespective vehicle in said line when said vehicles are rolledsuccessively to each said station, dynamic vehicle testing means at atleast one of said stations in energy transmission engagementsuccessively with a rotating wheel of each respective vehicle in saidline when said vehicles are rolled successively to said station, anddiagnostic test equipment operative simultaneously from difierentstations adapted for initiating a diagnostic test on at least onevehicle in said line prior to completion of a different diagnostic teston another vehicle in said line, whereby a large number of vehicles maybe diagnosed sequentially and substantially continuously for overalloperation as aforesaid including simulated road operation, thereby toprovide information on deficient conditions and performancecharacteristics of each vehicle in said line sufficient to enablecorrection without actual road testing or further general diagnosis, theimprovement which comprises a dynamometer included in said dynamicvehicle testing means operative from at least one of said stations andadapted for rotatable engagement simultaneously with both rear wheels ofeach successive vehicle in the diagnostic line sequentially, and anoscilloscope vehicle engine analyzer, operative from the station atwhich said engagement between rear vehicle wheels and said dynamometeris eifected, adapted to be actuated by electrical energy from the highvoltage side of the vehicle ignition system thereby to depict separategraphical wave form oscilloscope representations of the electricalignition input to respective engine cylinders.

2. The system of claim 1 in which said dynamometer comprises meansadapted to be driven by rotating rear wheels of successive vehicles insaid line, said wheels being driven by the engines of respectivevehicles at different speeds and difierent power outputs, and means toabsorb and indicate quantitatively power outputs so delivered by therespective vehicle engines through the respective vehicle powertransmission mechanisms to said vehicle wheels, whereby the operation ofthe engines and transmission mechanisms of successive vehicles in saidline can be diagnosed for road driving eifectively, quickly for eachvehicle, and in close time sequence for a large number of vehicles.

3. The system of claim 2 which comprises means adapted for operationsimultaneously with said dynamometer and said engine analyzer, timingtest means to illuminate the timing marks on the engine and to ascertainthe basic timing and the operation of the spark advance of the engine atdifierent engine speeds.

4. The system of claim 2, adapted further to shorten diagnostic time forrespective vehicles in said line and to accelerate movement of theentire said line, which comprises respective means, adapted foroperation simultaneously with said dynamometer and said engine analyzer,for measuring fuel pressure, rate of fuel flow, vehicle engine speed andvehicle wheel speed.

5. The system of claim 4 which comprises means adapted for operationconcurrently with said dynamometer, engine analyzer and fuel pressureand flow rate measurement means, for sampling vehicle exhaust gases atdifferent engine speeds and loads, and means for analyzing samples ofsaid vehicle exhaust gases to determine combustion efficiency of theengine, whereby the completeness, of diagnosis of each vehicle passingsaid point of exit at the end of said line is enhanced and is likewiseenhanced for all vehicles diagnosed.

References Cited by the Examiner OTHER REFERENCES Crouse, W. H.:Automotive Engines, McGraw-Hill Book Co., Inc. 1955, pp. 307 and 310, TL210 C72a Socony-Vacuum Cathode-Ray Engine Analyzer Instruction Book.Published by Socony-Vacuum Labora tories Research and DevelopmentDepartment, Pankboro, N.I., (1951), page 17.

RICHARD C. QUEISSER, Primary Examiner, DAVID CHONBERG, Examiner

1. IN A SYSTEM PROVIDED FOR RAPID, EFFICIENT, UNIFORM DIAGNOSES OF APLURALITY OF IN LINE CLOSELY FOLLOWING, INDEPENDENTLY, INTERMITTENTLYMOVING AUTOMOTIVE ROAD VEHICLES TO DETERMINE AND IDENTIFY DEFICIENTCHARACTERISTICS OF EACH THEREOF BY TESTING EACH SAID VEHICLE AT EACH OFA PLURALITY OF STATIONS AS SAID VEHICLE IS ROLLED IN NORMAL MANNER TOAND BEYOND EACH SAID STATION IN PROCEEDING TO A POINT OF EXIT, WHEREBYEACH VEHICLE WILL BE DIAGNOSED TO SUBSTANTIALLY THE SAME AND OVERALLEXTEND SUFFICIENT TO PROVIDE A MASTER RECORD OF ITS FAULST AND THEREBYPERMIT ITS REPAIR AND CORRECTION AS DESIRED SUBSEQUENT TO DIAGNOSIS,COMPRISING A DIAGNOSTIC PASSAGEWAY HAVING AN ENTRANCE AND STATIONS ALONGSAID PASSAGEWAY THEREBY ADAPTING SAME TO AN EXIT, CONSTRUCTIONAL MEANSSPACING SAID PLURALITY OF RECEIVE SAID LINE OF VEHICLES WITH ONE VEHICLEAT AT LEAST EACH OF A MAJORITY OF SAID STATIONS WITH WORKING SPACEBETWEEN SAID RESPECTIVE VEHICLES, MEANS DETERMINING THE WIDTH OF SAIDPASSAGEWAY AT LEAST SUFFICIENTLY WIDE TO PERMIT LENGTHWISE TRANSIT OFSAID LINE OF VEHICLES AND SUFFICIENTLY NARROW TO REQUIRE SUBSTANTIALLYLENGTHWISE TRANSIT OF EACH SUCCESSIVE VEHICLE IN SAID LINE THROUGH EACHSUCCESSIVE STATION, DIAGNOSTIC TEST EQUIPMENT OPERATIVE AT EACH SAIDSTATION ADAPTED FOR A DIFFERENT DIAGNOSTIC TEST SEQUENTIALLY ON EACHRESPECTIVE VEHICLE IN SAID LINE WHEN SAID VEHICLES ARE ROLLEDSUCCESSIVELY TO EACH SAID STATION, DYNAMIC VEHICLE TESTING MEANS AT ATLEAST ONE OF SAID STATIONS IN ENERGY TRANSMISION ENGAGEMENT SUCCESSIVELYWITH A ROTATING WHEEL OF EACH RESPECTIVE VEHICLE IN SAID LINE WHEN SAIDVEHICLES ARE ROLLED SUCCESSIVELY TO SAID STATION, AND DIAGNOSTIC TESTEQUIPMENT OPERATIVE SIMULTANEOUSLY FROM DIFFERNT STATIONS ADAPTED FORINITIATING A DIAGNOSTIC TEST ON AT LEAST ONE VEHICLE IN SAID LINE PRIORTO COMPLETION OF A DIFFERENT DIAGNOSTIC TEST ON ANOTHER VEHICLE IN SAIDLINE, WHEREBY A LARGE NUMBER OF VEHICLES MAY BE DIAGNOSED SEQUENTIALLYAND SUBSTANTIALLY CONTINUOUSLY FOR OVERALL OPERATION AS AFORESAIDINCLUDING SIMULATED ROAD OPERATION, THEREBY TO PROVIDE INFORMATION ONDEFICIENT CONDITIONS AND PERFORMANCE CHARACTERISTICS OF EACH VEHICLE INSAID LINE SUFFICIENT TO ENABLE CORRECTION WITHOUT ACTUAL ROAD TESTING ORFURTHER GENERAL DIAGNOSIS, THE IMPROVEMENT WHICH COMPRISES A DYNAMOMETERINCLUDED IN SAID DYNAMIC VEHICLE TESTING MEANS OPERATIVE FROM AT LEASTONE OF SAID STATIONS AND ADAPTED FOR ROTATABLE ENGAGEMENT SIMULTANEOUSLYWITH BOTH REAR WHEELS OF EACH SUCCESSIVE VEHICLE IN THE DIAGNOSTIC LINESEQUENTIALLY, AND AN OSCILLOSCOPE VEHICLE ENGINE ANALYZER, OPERATIVEFROM THE STATION AT WHICH SAID ENGAGEMENT BETWEEN REAR VEHICLE WHEELSAND SAID DYNAMOMETER IS EFFECTED, ADAPTED TO BE ACTUATED BY ELECTRICALENERGY FROM THE HIGH VOLTAGE SIDE OF THE VEHICLE IGNITION SYSTEM THEREBYTO DEPICT SEPARATE GRAPHICAL WAVE FORM OSCILLOSCOPE REPRESENTATIONS OFTHE ELECTRICAL IGNITION INPUT TO RESPECTIVE ENGINE CYLINDERS.